3 ch. voice reservation

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Jun 26th, 2001
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Two networks: Net A running VoIP and Net B running VoIPoFR, at this moment they are interconnected through a WAn link (TDM 256kbps)and working with VoIP.

I want to make sure this WAN link reserves BW for 3 voice channels, and limit it to only 3.

Suggestions? I would like just to modify configurations of routers that interconnect both networks. Sample configurations for that ??

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dgoodwin Tue, 06/26/2001 - 16:41
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You didn't mention what encapsulation you were using on the WAN link between Net A and Net B, but you would want to use LLQ (Low Latency Queuing) to prioritize the bandwidth required for 3 calls (how much that is depends on the codec used). LLQ documentation can be found at:


http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t7/pqcbwfq.htm


and


http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t2/dtfrpqfq.htm


As far as making sure that the simultaneous calls are limited to 3, just use the max-conn 3 command on the dial-peers that go across the WAN link between Net A and Net B.

mhori Wed, 06/27/2001 - 09:03
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Thanks a lot.


With max-conn 3 I will limit to 3 the number of simultaneous calls from one router in Net A to Net B,

but another router in Net A can place 3 more calls to Net B, so I will have 6 calls across the WAN.

VoIP is not configured in WAN routers, they just let traffic pass; how could I manage this?

Would be a good idea to make them work as tamdems?


Regards,

Marc

dgoodwin Wed, 06/27/2001 - 09:09
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You can't tandem switch VoIP calls, only VoFR or VoATM calls.


In that case it seems that the best answer is to add a gatekeeper to the network. Using that, you can have the voice gateways in Net A and Net B be registered in "zones" in the gatekeeper configuration, and it can be configured to assume how much bandwidth is available for the zone. So if all the gateways in each net use the gatekeeper to route the calls, the gatekeeper will not let the call be placed if all the bandwidth is already used up because there are 3 active calls.

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